Severance and Exit Costs (Schedule of Severance and Exit Costs) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2016
Restructuring Cost and Reserve [Line Items]
Document Period End Date				Sep. 30, 2016
Restructuring Reserve [Roll Forward]
Restructuring Reserve		$ 341		$ 341		$ 525
Supplemental Unemployment Benefits, Severance Benefits		46		46		150
Restructuring Charges				13
Payments for Postemployment Benefits				(113)
Restructuring Reserve, Settled with Cash				(197)
Lease [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve		265		265		338
Restructuring Charges	[1]	(15)		(5)
Restructuring reserved settled with cash and other adjustments				(68)
Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve		30		30		$ 37
Restructuring reserved settled with cash and other adjustments				(16)
Wireless [Member]
Restructuring Reserve [Roll Forward]
Severance Costs	[2]	5		9
Wireless [Member] | Lease [Member]
Restructuring Reserve [Roll Forward]
Restructuring Charges	[1]	(17)		(7)
Wireless [Member] | Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring Charges	[1]			9
Wireline [Member] | Lease [Member]
Restructuring Reserve [Roll Forward]
Restructuring Charges	[1]			2
Other Operating Income (Expense) [Member] | Wireless [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve, Accrual Adjustment			$ 41
Successor [Member] | Cost of Sales [Member] | Wireline [Member] | Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring Charges		$ 5		$ 2
Successor [Member] | Other Operating Income (Expense) [Member] | Wireless [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve, Accrual Adjustment					$ 20

[1] For the three and six-month periods ended September 30, 2016, $5 million (Wireline only) and $7 million ($2 million Wireless, $5 million Wireline), respectively, were recognized as "Severance and exit costs." For the six-month period ended September 30, 2016, $2 million (Wireline only) was recognized as "Cost of services."We continually refine our network strategy and evaluate other potential network initiatives to improve the overall performance of our network. Additionally, a major cost reduction initiative is underway, which may include headcount reductions, among other actions, to reduce operating expenses and improve our operating cash flows. As a result of these ongoing activities, we may incur future material charges associated with lease and access exit costs, severance, asset impairments, and accelerated depreciation, among others.

[2] For the three and six-month periods ended September 30, 2016, we recognized costs of $5 million (Wireless only) and $9 million (Wireless only), respectively.